adenocarcinoma

Question
I am a Ph.D. CAAB expert on this site for six + years.  I do a mammary check of my bitch every month.  The last check revealed a "rocky craggy" mass under the 4th left mammary gland that was not there one month prior.  I immediately took the dog to my veterinarian (experienced and trustworthy).  He agreed that it "felt" malignant.  We scheduled mastectomy and spay (the bitch is presence 8-1/2 years old, I acquired her over age 2 from a negligent home as a rescue).  The pathology results came back today:  adenocarcinoma.

My veterinarian told me he excised a large portion under the tumor and no veins were involved, no apparent metastasis, we caught it "in time".  He also advised (as I would have done anyway) a monthly mammary check and I will do a "well check" visit to him in about six weeks so he can teach me how to palpate the lymph nodes behind the mammary gland (inguinal) to be certain they feel "normal".  This is a Toy Poodle.  I was able to locate her breeder (due to information given me by the person from whom I adopted/rescued her).  The breeder insists she has no history of mammary cancer in her line but, naturally, I don't believe her since it has come to my attention that the Toy Poodle is at very high risk of same.

My question:  is a line mastectomy and lymph node removal necessary at this point or should I wait to see if another "lump" appears?  I want to be aggressive here as this dog is my "last" dog in a lifetime of many dozens of dogs (many of whom were rescues).  Should I consult a Veterinary oncologist or internist for further evaluation?  I appreciate your input.  Jill Connor, Ph.D., CAAB, Canine Behavior expert.

Answer
Before doing anything, you might let an oncologist review the pathology report to see the grade of malignancy and which type of mammary adenocarcinoma is present.  Some are very aggressive and other as not.  Then if it is a malignancy, I would have the rest of that quadrant removed along with the lymph node.